Appliances requiring thermal insulation in the panel walls thereof, especially refrigerators and freezers, are generally manufactured by providing an outer structural shell of sheet metal, inserting therein an interior liner of a plastic material, and foaming a polyurethane insulation in-situ therebetween. The foamed-in-place insulation adheres to the metal shell and the plastic liner, and cannot thereafter be removed if it fails as a result of, for example, deterioration of the insulation, wetting of the insulation due to the condensation of moisture, etc. Alternatively, some manufacturers of appliances merely place batts of thermal insulation between the outer structural metal shell and the interior plastic liner which is connected thereto. In either case, if the insulation fails, it cannot be removed and replaced easily with fresh insulation in order to restore the efficiency of the appliance. When the thermal performance of the insulation degrades, the appliance requires more energy to operate. A further disadvantage associated with foamed materials is that they oftentimes contain unacceptable amounts of chlorinated fluorocarbons.
U.S. Pat. No. 4,974,914 discloses a refrigerator having an outer metal shell and an inner polymeric liner with foamed-in-place insulation therebetween. The insulation is not easily removable from the disclosed cabinet construction.
It would be desirable to produce an appliance cabinet which would allow ready access to the insulation for the replacement or repair thereof. It would also be desirable to produce an appliance cabinet which employs insulation materials having high R-values (R-value is the common terminology applied to Thermal Resistance and is a measure of an insulation product's ability to retard heat flow) to yield an energy efficient insulation appliance. It would further be desirable to produce an appliance cabinet which employs insulation materials having high R-values which are devoid of unacceptable amounts of chlorinated fluorocarbons.